My PhD dissertation (Sciences Po Paris & Université Saint-Louis) considers the dilemma generated by immigration and diversity for political elites in two culturally and linguistic distinct sub-national communities: Flanders (Belgium) and Quebec (Canada). For such communities, immigrant integration represents both opportunities and challenges. Immigration might increase the relative demographic strength of the sub-national community yet, it might also weaken its cultural or linguistic cohesion. Focusing on the 1999-2014 timeframe and using discursive institutionalism, I ask how subnational elites respond to this dilemma. Using discourse analysis, I identify the position of members of regional parliaments and their rhetoric on four dimensions of immigrant integration (institutional, demographic, linguistic, and cultural). Contrary to other researches that have focused only on sub-nationalist and regionalist party positions (SNRP), my focus on political discourse and all elites allows me to show how ideas circulate and evolve through legislatures. My results run contrary to some expectations from immigration studies and federalism theory. I show that key arguments are shared between political elites when it comes to the linguistic, demographic and cultural dimensions of immigrant integration. Nevertheless and independently from the conceptions of integration put forward, I show that clear divergences remain when it comes to federal-subnational institutional arrangements for immigrant integration.